X-ray-induced mutation of Bacillus sp. MR10 for manno-oligosaccharides production from copra meal
X-ray-induced mutation of Bacillus sp. MR10 for manno-oligosaccharides production from copra meal
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X 射线诱导的芽孢杆菌突变。
DOI：
10.1080/10826068.2016.1252929
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发表时间：
2017
影响因子：
2.9
通讯作者：
and Chartchai Khanongnuch
中科院分区：
文献类型：
--
作者：
Siriporn Chaikaew;Apinun Kanpiengjai;Jenjira Intatep;Kridsada Unban;Pairote Wongputtisin;Goro Takata;and Chartchai Khanongnuch
本研究证明了X射线辐射在芽孢杆菌脂肪酶生产缺陷菌株改良中的有效性。MR 10进一步应用于从农业副产品脱脂椰肉粉（DCM）发酵生产甘露寡糖（MOS）。基于其缺陷脂肪酶活性以及其β-甘露聚糖酶生产性能来筛选获得的突变体。在10株突变株中，菌株M7的脂肪酶活力最低（0.05 U/ml），β-甘露聚糖酶活力与出发菌株相近（22 U/ml）。突变体M7有效地将DCM水解为MOS，其中低聚合度（DP）寡聚物包括甘露三糖（M3）、甘露四糖（M4）和甘露戊糖（M5）作为主要产物。突变株M7的DCM水解产物与野生型有明显差异，但其纯化的β-甘露聚糖酶的生化性质和催化性质与野生型相似。表观分子量为38 kDa的两种纯化的β-甘露聚糖酶在pH 5-7和45-55°C下表现出最佳活性。Co ~（2+）和Hg ~（2+）几乎完全抑制酶活性，而Ba ~（2+）、Fe ~（3+）和2-巯基乙醇对酶活性有明显的激活作用。这两种酶对刺槐豆胶、甘露聚糖、DCM和瓜尔豆胶都具有很高的特异性。因此，突变体M7具有从低成本DCM商业化生产高质量MOS以进一步应用于饲料工业的潜力。
The present study demonstrates the effectiveness of X-ray radiation in strain improvement for defective lipase production byBacillussp. MR10 for further application in the fermentative production of manno-oligosaccharides (MOS) from agricultural by-product, defatted copra meal (DCM). The mutants obtained were screened based on their defective lipase activity together with their β-mannanase production performance. Among 10 selected mutants, the strain M7 was the highest promising mutant regarding the smallest lipase activity (0.05 U/ml) and the retained β-mannanase activity similar to the parental strain (22 U/ml) were detected. The mutant M7 effectively hydrolyzed DCM to MOS with low-degree of polymerization (DP) oligomers including mannotriose (M3), mannotetraose (M4), and mannopentose (M5) as the main products. Although the pattern of DCM hydrolysis products of mutant M7 was distinctly different from wild type, the biochemical and catalytic properties of purified β-mannanase of mutant were similar to those of wild type. Both purified β-mannanases with apparent molecular mass of 38 kDa displayed optimal activity at pH 5–7 and 45–55°C. Co2+and Hg2+nearly completely inhibited activities of both enzymes, whereas Ba2+, Fe3+, and 2-mercaptoethanol obviously activated enzyme activities. Both enzymes showed high specificity for locust bean gum, konjac mannan, DCM, and guar gum. Thus, the mutant M7 has a potential for commercial production of high-quality MOS from low-cost DCM for further application in the feed industry.